Print score as booklet

As a user i want to be able to print the Score as a booklet.
I want to use A3 paper in landscape mode.
Then I can print 2 A4 pages (in Portrait) next to each other, on both sides.

The trick has to be that if I completely printed the Score I fold the A3 landscape paper to A4 portrait format (so fold in once over the middle line).

I have to start with page 1, when I turn the page, page 2 and 3 have to be next to each other.

But this means that Pages should be printed as following on paper (Example is A3 paper, with left and right the page that should be printed. First is front of the paper, second is the back of the paper.
In this example I have 12 A4 pages

Front Pape 1:
-----
|12|1|
-----
Back Page 1:
-----
|2|11|
-----

Front Pape 2:
-----
|10|3|
-----
Back Page 2:
----
|4|9|
----

Front Pape 3:
----
|8|5|
----
Back Page 3:
----
|6|7|
----

So in this example you have 3 A3 pages, that contain 12 A4 Pages.
If you only print 11 pages the left side of the first front page should be an empty page.